Graphene is a single planar sheet of sp2 bonded carbon atoms. Monolayers to several layers of this two-dimensional structure have been widely examined not only for their interesting physical and chemical properties, but also as potential materials for electronic devices. Graphene provides remarkable transport properties such as high carrier mobility, room temperature quantum hall effect, and ballistic transport. Two-dimensional graphene, however, is a semi-metal with a zero band and is generally not suitable for transistor applications. To that end, graphene nanoribbons, with widths small enough to impose lateral confinement effects, are expected to open up a band gap making them a semiconductor.
Lithographical patterning of large graphene layers has been widely used to create large graphene ribbons with rough edges (Bolotin, et al. 2008). Further, lithographic techniques have been used in conjunction with electrostatic force to obtain narrower graphene ribbons (Liang, et al. 2009). In both of these lithography-based techniques, the graphene ribbons that are produced exhibit rough edges making them unsuitable for many semiconductor applications. Alternative methods, such as chemical methods for producing graphene nanoribbons, have produced graphene nanoribbons with smooth edges, but these techniques have required extensive chemical treatments to produce the nanoribbons (Li, et al. 2008). In any event, known methods of producing graphene ribbons, including graphene nanoribbons, are only capable of producing graphene ribbons with rough edges or are only capable of producing graphene nanoribbons with smooth edges after extensive chemical treatments. Furthermore, none of the known methods address how to produce long, narrow, and smooth-edged graphene nanoribbons without extensive chemical treatments and then transfer these graphene nanoribbons to a desired substrate, which is of great importance in constructing semiconductors.